Tilted rotary retort industrial furnace

ABSTRACT

A tilted rotary retort industrial furnace for processing metal workpieces in a controlled atmosphere which includes a heated gas-tight chamber rotatably mounted at an incline of 45* ( + OR 5*) to the horizontal to turn continuously in one direction with the interior of the chamber being partitioned into successive intercommunicating zones, there being means provided for feeding workpieces into the chamber and for facilitating step-by-step gravitational advance of such workpieces through the zones to a discharge tube means having substantially less transverse dimension than the chamber and permanently aligned with and rotating with the chamber and disposed within and beneath the surface of a liquid quenching medium to effect a liquid seal.

United States Patet [1 1 Davis 1 June 4, 1974 1 TILTED ROTARY RETORT INDUSTRIAL FURNACE [76] lnventor: Alvin W. Davis, c/o Al Davis Co.,

2925 Harding Hwy., Apt. 7, Lima, Ohio 45804 [22] Filed: Sept. 1, 1972 211 Appl. No; 285,678

Primary Examiner--Roy Lake Assistant Examiner-James F. Coan Attorney, Agent, or Firm-John S. Roberts, Jr.

[ 5 7 ABSTRACT A tilted rotary retort industrial furnace for processing metal workpieces in a controlled atmosphere which includes a heated gas-tight chamber rotatably mounted at an incline of 45 (:5") to the horizontal to turn continuously in one direction with the interior of the chamber being partitioned into successive intercommunicating zones, there being means provided for feeding workpieces into the chamber and for facilitating step-by-step gravitational advance of such workpieces through the zones to a discharge tube means having substantially less transverse dimension than the chamber and permanently aligned with and rotating with the chamber and disposed within and beneath the surface of a liquid quenching medium to effect a liquid seal.

12 Claims, 15 Drawing Figures PATENTEUJUN 41974 3.814401 SHEU 1 1F 6 FIG. 1

PATENTEDJHN 4 e974 SHEET 2 OF 6 QJQ 5 g: h

TILTED'ROTARY RETORT INDUSTRIAL FURNACE BACKGROUND OF THE INVENTION The present invention relates broadly to the art of industrial furnaces.

More particularly this invention relates to an industrial furnace in which small metal workpieces or parts such as screws, nuts, bolts, washers, etc., are subjected to heat treatment in a controlled gaseous atmosphere for hardening, case hardening, carbonitriding or carburizing the same.

Still more particularly, the invention relates to such an industrial furnace in which such small metal workpieces or parts pass through an inclined, rotary retort or gas-tight chamber provided with partitions defining successive treatment zones having apertures providing communication between the zones and vanes in the zones for lifting and guiding the parts from zone to zone successively. The parts pass from the lowermost zone to a rotary discharge portion having a lower end permanently located within and below the surface of a quench bath.

The furnace of the invention is primarily intended for processing small parts such as screws, bolts, nuts, washers, and the like of 1/4 inch thread size and smaller but will handle larger parts having no dimension greater than one inch at a reduced production rate.

The furnace can be sized for larger parts but it is presently sized for a production of about 1,000 lbs. an hour of hardening or about 350 lbs. an hour of light case carbonitriding to a case depth of .003 to .005 inch. It is capable of carburizing at a reduced production rate depending upon the required case depth and concentration.

Hardening is usually confined to carbon and lowalloy steels and in applying the furnace of the invention involves heating the steel to its austenitizing temperature and then quenching (rapid cooling) it, which is usually done by immersion in oil, water or salt.

Carbonitriding, which is also known as dry cyaniding, gas cyaniding, nicarbing and nitrocarburizing, is a case hardening process in which carbon and alloy steels are held at an elevated temperature (austenitizing) in a controlled atmosphere including a suitable hydrocarbon gas or liquid, (of which methane is probably most widely used) and ammonia, from which the parts absorb carbon and nitrogen simultaneously, and are then usually quenched.

Carburizing is a means of increasing either or both carbon concentration and depth at the surface of steel parts. It is now usually done in a controlled atmosphere of or including hydrocarbon additives, and at a somewhat higher temperature than carbinitriding. it sometimes includes a slow cooling requirement for which the furnace of the invention is not presently applicable. However, the furnace of the invention can be used where the carburized parts are to be directly quenched from the retort as in carbonitriding.

Controlled atmosphere, when used here, refers to a protective atmosphere used during the hardening, carbonitriding or carburizing process to prevent surface oxidation, scaling, decarburization, and/or to maintain, correct, or increase the carbon, and/or nitrogen content of the steel.

The are prior art arrangements for heat treating metal parts such as embodied in US. Pat. Nos. 3,360,252 to Westeren, 3,059,911 to Samuel et al, 3,464,683 to Enk, 3,176,970 to Holcro'ft, and 3,556,498 to Sheahan.

However, these disclosures do not provide for a continuous flow of parts to and through a retort, direct quenching immediately thereafter, and continuous onward movement to a further work station or receptacle.

Particularly, the prior art does not provide a furnace having a fixed high angle of inclination to 45 1' 5, 11 gas-tight retort therein mounted for continuous 360 a rotation with the retort being compartmentalized to provide successive holding zones so that the parts to be treated are properly processed during passage through the zones and in which a discharge end rotating with the retort is permanently located in and beneath the surface of a quenching medium.

Likewise, the prior art does not provide a combined elevating and conveying means for continuously lifting quenched parts and conveying the same forwardly over the upper edge of a quench tank to primarily drop, not chute convey, the work to the next operation.

While Westeren might have an inclined retort, the same is oscillated, not rotated, and the discharge to a quenching medium, as well as the gas inlet requires a mechanical seal between a turning and a stationary part.

Further, Westerens retort or tube is of constant diameter from end to end which as a practical matter precludes direct immersion of its lower end into and below the surface of the quenching medium, or if accomplished by reducing the diameter of the retort, the reduction in work load and production rate would result in an economically unfeasible structure. Thus, assuming an 18 inch constant diameter retort in Westeren, the insertion of a discharge end into oil or water at a 45 angle to the horizontal would require over 25 inch longitudinal surface area of the oil or water bath. As the angle to the horizontal decreases the longitudinal surface area of an oil or water bath would necessarily have to increase. The heat losses from the furnace would render such an arrangement impractical, water would convert to steam which would severely interfere with controlled atmosphere quality and a quench oil would require economically unfeasible cooling equipment and perhaps might be uncontrollably hot. Also, the ability to maintain temperature of the work just prior to quenching is doubtful as both the temperature and the time required to get the work into the quench from the furnace hot zone is critical. Consequently the Westeren design arrangement could not be applied with any degree of practicality to a self-sealed, i.e., beneath the quenching liquid, retort.

The structure of Samuel et al, while capable of tilting to discharge to a quench bath, is limited to use as a batch operation rather than a continuous'flow. Additionally, the front extension of Samuel et al has only a slightly less transverse dimension than the transverse dimension of the chromizing chamber, so that the structure suffers from the same drawbacks as the Westeren structure. Likewise, the heat treating is effected in a tumbling action with the retort in a more or less horizontal (less than 45) position.

retort furnace in which the interior of the retort is subdivided into successive zones in such a manner that parts can be isolated in batches in their continuous travel through the retort to the quenching medium or bath.

Additionally, itis desirable that the invention provide a combined elevating and forward conveying means for lifting the parts and moving the same forwardly to discharge from the quench bath tank.

Likewise it is desirable to provide an integrated system for processing workpieces which in addition to the inclined rotary retort includes a feed system operatively associated with the upper workpiece-receiving end of the retort that is effective to deliver measured or metered quantities of workpieces to be processed in the retort.

SUMMARY OF THE INVENTION Therefore, in order to achieve the foregoing advantages and to overcome the above and other shortcomings in prior rotary retort industrial furnaces, this invention provides a tilted rotary retort furnace for heat treating metal parts in a controlled atmosphere which includes a gas-tight chamber rotatably mounted at an an incline of 45? (:5?) to the horizontal. Means are provided to rotate the chamber continuously in one direction. The rotation is directionally non-reversing and either clockwise or counterclockwise. The interior of the chamber is provided with partitions defining successive zones. The partitions are provided with apertures providing communication between the zones and radial vanes and deflectors are provided for lifting and guiding the material from zone to zone-successively. The chamber has a rotary discharge portion having one end communicating directly with the lowermost zone and its other end within a quench tank or liquid quenching medium accommodating means and permanently located and rotated beneath the surface of a quench bath therein.

A quench wheel also inclined as above is connected with and rotates with the rotary discharge portion of the chamber for deflecting the material under treament 90 and coincidentally lifting and moving the same through and from the quench medium to a discharge point outside of and to the rear of the quench tank.

I The invention further provides an integrated, i.e., bolted and permanently welded, compact and spacesaving structure including a frame, a quench tank, and

acombined feed system, heatable, gas-tight holding and conveying processing enclosure (retort) having a constantly immersed discharge portion, drive means for rotating the same and also including a quench inundator and combination elevator-forward-conveyor quench wheel, the arrangement providing automatic metering of. parts to be treated into, through, and out of the enclosure and quench system. 1

The invention also broadly provides a rotary retort chamber inclined at an angle of 45 5, a pluralityof axially spaced partitions arranged perpendicular to the axis thereof and each having a plurality of apertures therein, compartmentalizing the interior of the chamber into a plurality of intercommunicating zones and radial vanes between the partitions corresponding in number to the number of apertures in adjacent partitions so as to subdivide each zone into a like plurality of sections.

Further, the apertures in some partitions are arranged at different radial distances from the center line of the chamber than are the apertures in other partitions and axily extending deflectors are associated with the apertures in at least some of the partitions so as to facilitate flow of parts to be treated from zone to zone successively.

Consistent with the immediately aforedescribed arrangement, the feed system includes a number of individual tubes corresponding in number to the number of sections in the zones and operatively related with the uppermost zone to feed parts into the several sections therein so that parts passing through the chamber to a quench discharge are isolated in separate sections in each zone throughout the entire treating process.

In addition the invention provides a feeding system for delivering workpieces to the rotary inlet end of the processing components of the furnace or retort which will'measure or meter the delivery of such workpieces to the upper rotary workpiece-receiving end thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 3 is a cross sectional view taken on line 33.of

FIG. 2-and looking toward the discharge end of the retort proper; FIG. 4 is a similar view taken along line 4-4 of FIG.

2 and looking toward the infeed end of ,the retort proper;

FIGS. 5 to 10 illustrate the partition plate structures that subdivide the retort into successive zones, as viewed from the right in FIG. 2;

- FIGS. 1 1 and 12 illustrate the infeed end of the retort in longitudinal section and end elevation, respectively;

FIGS. .13 and 14 areviews illustrating the upper and lower ends of thequench wheel; and

FIG. '15 is a diagrammatic view illustrating the fur-. nace of the invention and an accompanying parts feeder arrangement.

DETAILED DESCRIPTION OF'PREFERRED EMBODIMENT As indicated in the drawing, FIG. 1, the tilted rotary retort industrial furnace of this invention includes a steel base structure A constructed of suitably cut channels, angles, and plates to provide a quench tank por tion 1 at one end and a furnace support portion 2. The fumace-B is a steel shell 3 lined with firebrick and other heat insulation 4 to provide a combustion or electrically heated chamber. In this gas fired version, four valve controlled gas burners 5, two at each end of the furnace communicate with'the interior of the combustion chamber, and a flue 6 is connected to the upper end thereof so as to provide a direct fired furnace. The furnace is supported at an angle of 45(: 5) with the uppermost end constituting the inlet end of a retort for the parts to be treated and the lowermost end the quenching and discharge end of such retort. The pair of burners at the upper end of the furnace chamber are angularly spaced on the lower half of this end while the pair of burners at the lower end of the furnace chamber are angularly spaced in the upper half of such lower end. The flue is located between the burners at the upper end of the furnace.

1n the embodiment illustrated the furnace shell is approximately 6 feet in diameter and 73 inches in length. At each end of the lined shell is an aperture 7 t0 accommodate the opposite, respective feed and discharge ends 8 and 9 of the retort proper C.

The retort includes a work treating, i.e., heating and atmosphere processing chamber 10, the upper work feeding end 8 and the lower direct quenching and discharging end 9. A parts feeder D is connected to and integrated with the upper end of the treating chamber and a quench conveyor wheelE is integrated with the lower discharge end of the heating chamber.

The retort is supported for rotation within the furnace and drive means F is provided for rotating the retort through 360 in one direction.

In the illustrated embodiment, see FIG. 2, the retort chamber has a length of about 37 inches and an outside diameter of about 36 and three eighs inches. The interior of the chamber is subdivided into six compartments, 1], l2, l3, 14, 15 and 16 by opposite end plates 17 and 18 and partition plates 19, 20, 21, 22 and 23. All of the plates are of 3/16 inch thick alloy steel having an outside diameter of 36 inches. The uppermost and lowermost end plates 17 and 18 are each provided with a central hole of 8% inch inside diameter within which are welded the ends of the feed accommodating tube 8 and the discharge tube 9, respectively. Each of these tubes are of alloy steel of 3/8 inch wall thickness, 8 inch inside diameter, and 22% inches in length. The five other or partition plates are of the same thickness and outside diameter as end plates 17 and 18. The seven plates are welded inside the shell and are spaced 6 inches from one another. The second to the sixth plates do not have a central hole. Instead, the second plate 19 is provided with six holes 25 of 4-inch diameter drilled 60 apart on a -inch radius from the center of the plate. The third plate 20 has six 4-inch diameter holes 26 similarly spaced but centered on a 12-inch radius, the fourth plate 21 has six 4-inch diameter holes 27 similarly spaced centered on a 16-inch radius, the fifth plate 22 is similar to the fourth with the holes 28 on a l2-inch radius, and the sixth plate 23 has its 4-inch diameter holes 29 centered on an 8-inch radius, see FIGS. 5 to 10.

Between each pair of adjacent plates are six vanes 30, each of 3/16 inch thick alloy steel, 6 inches in width and 17% inches in length. The vanes are welded to the plates, to the shell, and to each other around the center of the plates so that the vanes are 60 apart and assuming clockwise rotation are tangent to the trailing side of the respective holes on the second, third, and fourth plates, 19, 20 and 21 and to the leading side of the holes on the fifth and sixth plates, 22 and 23. Thus. the assembly of shell, plates, and vanes subdivides the treating and processing chamber into six successive zones, each further subdivided into'six compartments. Parts deflectors 31 are made of 4 inch inside diameter 3/16 inch thick tubing of 6-inch lengths cut in half lengthwise to provide sets of deflectors for welding to the vanes and betweencertain of the plates around one-half the circumference of the holes or apertures therethrough. Deflectors are provided and associated around one-half of the circumference of the apertures in the plates 19, 20, 22 and 23 constituting the second, third, fifth, and sixth plates. The fourth plate 21 has its apertures 27 on a l6-inch radius so as to be disposed adjacent the inner wall surface of the retort and thus no deflectors are necessary. Additionally, the deflectors are on the circumferential side of the apertures closest to the inner periphery of the chambers between the first and second and second and third plates and on the opposite circumferential side of the apertures between the fourth and fifth and fifth and sixth plates. No deflectors are necessary between the sixth and seventh plate since the 8-inch inside diameter central hole in the seventh plate is sub-divided into six discharge openings by the vanes welded between the sixth and seventh plates.

The aforedescribed structure constitutes the processing treatment area proper. The retort or furnace is completed by the parts feeder D which is integrally connected to the upper end of the treatment area and by the lifting and forward conveying quench wheel E integrally associated with the discharge conduit from the treatment area. A

The parts feeder is a combination volumetric metering device and purgechamber with'gravity-actuated valves for controlling atmosphere effluence and parts entry. This parts feeder is fed by a standard, commercially available elevator type conveying apparatus, such as a bucket elevator of the type widely used in industry.

The parts feeder D comprises a casing including a round bottom steel plate 32 that is 1/4 inch thick and of 36-inch outer diameter, a side wall 33 of 16 gauge steel 12 inches wide by 9 feet 5% inches in length, is rolled to 36-inch diameter and welded to the exterior of the bottom plate. To the interior of the outer end of the wall is welded a 1 /2 inch by 1% inch by l/4 inch angle 34, 9 feet 6 inches in length and rolled to a 36- inch outer diameter ring with the leg directed inwardly. A round top-steel plate 35 of 3/16 inch thickness and 36-inch outer diameter is removably connected to the leg of the angle, this leg being drilled and tapped to ac-.

commodate 1/4 inch cap screws disposed through openings drilled through the top plate. Six vanes 37 of l/8-inch thick steel plate 12 inches wide and 17 /8 inches long are welded to the bottom plate and side wall at angular spacing so as to subdivide the feed easing into six compartments 38. The top plate is provided with six vanes 37 and with six apertures 39 of 2- inch diameter, drilled with their centers on an 8-inch radius from the center of the top plate. The edge of each aperture 39 is 1/16 inch away from each vane 37' on the top plate and on the leading face thereof as regards a clockwise direction of rotation. A semicylindrical deflector piece 40 of 3-inch length is welded to the top plate around the side of each aperture closest each valve plate and another leg 47 bolted to a hinge- 48 secured to the adjacent deflector- A short length-of pipe coupling 49 is welded to the inner side of the top plate around each aperture and a pipe elbow 50 is threaded to each coupling with the open end thereof directed toward the side wall of the chamber. Each pipe coupling and elbow and its associated valve constitute a parts feeder throat and a first purge stage or zone as explained herein-after, while a second purge stage or zone exists in the balance of the interior of each sector or compartment of the feed chamber interior. I

The exterior of the bottom plate of the feeder has a I-inch thick steel ring 51 of l3 /-inch outer diameter and 8%-inch inner diameter welded thereto. This ring is drilled and tapped to receive bolts or cap screws 52 that pass through holes in a steel ring or pipe flange 53 i that is welded to the exterior of the main feed accommodating tube 54 54 that extends from the upper end of the treatment chamber proper. Six 24 /i-inch long distributor tubes 55 of2 A-inch inner diameter are welded to holes provided in the bottom plate so as to provide communication between the individual compartments of the feeder casing and the individual compartments of the upper chamber of the retort proper. Thus, the feeder assembly can be separated from the retort, also the top plate of the feeder casing can be removed so as to permit interchanging of the elbow shaped feeder throats.

The other major component of the furnace is the quench conveyor wheel E. As indicated, the final or lowermost zone of the retort proper communicates with an integrated discharge tube assembly; that includes a portion 56 permanently below the level of the quench medium in the quench tank. The-quench wheel structure .includes a centrally apertured first or top plate 57 about 6 feet 6% inches in diameter secured to a tube 58 that in effect is a continuation of the discharge tube proper, as described hereinafter and extending perpendicular to the axis thereof. A centrally apertured second or bottom plate 59 of less outer diameter, is disposed parallel to the top plate and spaced from the end of the tube portion 58 secured to the top plate. These plates are about 3 inches apart. A ring 60 of L-shaped cross section has oneleg 61 welded to the top plate and its other leg 62 extending radially inwardly about 9% inches toward the axis of the discharge tube. This other leg' 62 of the ring 60 is spaced about 4% inches from the bottom plate. Secured to the inner face of such other leg and the outer periphery of the bottom plate are a plurality of angle shaped lifting vanes 63. These vanes are 9% inches along one leg and 5% inches on the other. Assuming clockwise rotation, the long leg is uppermost. The integration of the plates, ring, and vanes with each other and with the discharge tube provide a parts accommodating wheel. A heavy steel roller accommodating ring 64 is welded to the bottom plate around the aperture therein.

The rear wall of the quench tankhas an inset portion 65, including a wall 66 extending at an angle of 45. This angled wall is apertured at 67 and on its upper face it carries a bracket structure 68 which rotatablysupports two 4-inch diameter flanged wheels 69 that ride on the heavy steel ring 64 on the bottom of the quench wheel. The aperture 67 accommodates the oil-gas inlet pipe arrangement. This inlet pipe arrangement includes a central gas pipe 70 having a parts deflector 71 spaced from its outlet end. The length of this pipe is sufficient to introduce the gas into the discharge tube above the level of the quenchmedium so that the latter constitutes a liquid seal. Surrounding the lower end of this pipe 70 is a larger diameter and shorter oil inlet pipe 72 terminating at the level of the 1 bottom plate of the quench wheel. A ring 73 is welded to the exterior of the gas pipe in slightly spaced relation to the terminal end of the oil pipe. This ring constitutes an oil deflector plate and causes the incoming oil to enter the quench wheel in sheet form flow closely adjacent the bottom plate of the quench wheel. This oil flow prevents parts from lodging between the oil pipe and quenchwheel. The inlet pipe arrangement is completed by a gasketed ring structure 74 bolted to the angled plate of the tank rear wall inset and around the aperture 67 therein. I

The upper end of the retort assembly is supported by a pair of circumferentially spaced unflanged wheels 75 of the same diameter as the lower wheels. The upper wheels are carried by brackets secured to the loading end of the furnace shell structure.

The discharge tube 9 of the retort has a pipe flange 77 at its end and the tube part 58 of the quench wheel also has a pipe flange 78 at its end. As assembly 79 of drive sprocket and gaskets is disposed between these pipe flanges and all these components are bolted together to integrate the retort and quench wheel.

With the particular mounting disclosed, the heavy ring on the quench wheel takes the entire end thrust load of the retort assembly and about one-half of the total radial load.

The drive system includes a motor driven variable speed drive 80 and a jackshaft assembly 81. The jackshaft assembly is a means of adapting the drive to the 45 angle of the sprocket, mounted between the pipe flanges 77 and 78 of the interconnection between the retort and quench .wheel; 1

A blower, not shown, for supplying combustion supporting air is mounted on the same platform 82 that supports the variable speed drive 80. This blower would not be utilized if the furnace was electrically heated. In an electrically heated furnace, heating-elements would be mounted in supporting slots cut in the face of the refractory material lining on the area thereof surrounding the main or largest diameter portion-of the retort.

A parts discharge chute 83 is secured to the rear of the quench tank to have an inlet end to underly the upper portion of the vaned end of the quench wheel.

In operation of the furnace of the invention, the parts, i.e., screws, bolts, nuts, etc., to be treated are lifted by a parts elevator which drops the same into the compartments at the open end of the feeder assembly, which being connected to the retort rotates therewith. A suitable parts elevator 84 shown diagrammatically in FIG. 15 includes a vibratory feeder which gently feeds the parts from a supply hopper 85 at an adjustable rate to a cleated belt. This eliminates the dragging of the belt through the mass of parts in the hopper. It also means less power consumption and less wear. The vibratory feeder does not overload the cleats, thus eliminating spillage of parts from the ascending belt. The discharge chute'is angularly adjustable and the supply hopper is of the type that is provided with an adjustable outlet gate. Any spillage or overflow from the rotating parts feeder is returned to the supply hopper via chute means 89 diagrammatically illustrated in FIG. 15. Fresh, i.e., cool quench oil and the controlled atmosphere gas are introduced into the lower end of the quench wheel and into the retort discharge tubing respectively. The controlled atmosphere gas flows toward the upper or feed end of the furnace and retort structure to a bleed off through the flapper valves located in the feeder D when the same are open. As the parts are introduced into the separate, internal compartments of the turning feeder assembly, they are metered through the gravity actuated, controlled atmosphere effluent valves where they are slowly purged in two stages, the first stage occurring in the feeder throats and the second in the main portion of each compartment in the interior of the feeder. After thorough purging, the parts feeder feeds the parts into the distributor tubes, each of which in turn feeds and confines parts into one of the six compartments located in the uppermost or first elevation of the heating zone retort. As each of the compartments are rotating around, over, and under the longitudinal axis of the retort proper which is permanently set at 45(:t from the horizontal and as the distributor tube delivers parts to the uppermost compartment of the uppermost elevation, and since each compartment is separated from the other compartments at its same elevation, the retort must rotate about 360 before parts drop from the uppermost compartment into the next lower compartment through the circular hole in the base (partition plate) of each upper compartment. This circular hole is always above the point of entry into a compartment at the moment the parts are received into that compartment.

The radially extending vanes separate each of the six retort elevations into six individual compartments at each elevation. The arrangement of compartments, i.e., vanes, partition plates, and circular holes are such that parts in one compartment are kept separated from parts in any other compartment until they are discharged from the furnace retort into the quench wheel.

The volumetric metering device of the feeder incrementalizes the parts, in this size furnace, into 3-pound lots. During rotation, the parts are raised by the vanes at each elevation and then lowered until they pass through the respective holes in the bottom (partition) plate of each elevation into the next subjacent compartment.

In the lowermost elevation, the parts in each compartment are raised to and drop into the discharge or quench tube within which the parts are at once quenched and delivered to the quench conveyor wheel. As the parts enter this wheel, they are deflected by 90 and slide along the front plate of such wheel until the V-shaped vanes or buckets lift the same upwards and responsive to the rotation of the wheel, drop the parts onto a chute for delivery to further processing equipment or for storage.

Thus, the quench wheel is a combined lifter and forward conveyor for moving the parts upwardly and outwardly of the quench tank.

It is to be pointed out that the cooperative structural relationship of the plates that subdivide the retort into successive zones, the radial vanes that subdivide each zone into a plurality of sections, the holes providing intercommunication between the sections of successive zones and the deflector plates utilized with the holes that are not adjacent the periphery of any zone ensures that the parts being treated move through 360 in each zone. Thus, responsive to rotation of the retort about its axis, the parts effect a step-by-step gravitational ad-' vance through the retort from zone to zone so as to be subjected to heat treatment as they advance through the retort for direct discharge into a quenching medium along a path that is the same as the angle of inclination of the retort. The parts are diverted through an angle of in the quench wheel and then lifted and forwarded out of such wheel to a gravity discharge.

Further, in the operation of the structure of the illustrated embodiment the drive system rotates the retort at a speed of about or approximately 1 RPM for hardening and about 1/3 RPM for carbonitriding.

In connection with the industrial furnace of the invention, it is to be emphasized that the discharge and- /or tube communicating between the bottom plate of the retort proper and the quench bath is of substantially less diameter than the diameter of the retort paper. In the illustrated example, the discharge tube is of 8 inches internal diameter and the retort proper is of 36 inches internal diameter. The reason for this substantial reduction in size between the discharge tube and the retort is to hold to a minimum the heat loss from the retort proper to the subjacent quench medium. In other words, at the range of temperature applied during the processing of metal parts, both the wall of the discharge tube and the line-of-sight relationship of the hot retort interior to the quench bath necessarily transfers heat to the cooler quenching bath. Whichever quenchant, i.e., oil, water or salt is used its temperature must be economically controllable. To prevent excessive heat transfer to the quenchant the effects of both conduction from the discharge tube, and the direct radiation from the retort proper, the discharge tube diameter should be kept to a minimum. The unique retort design of this invention permits restriction of the discharge tube diameter to main retort diameter at a ratio of l to 4.5 which results in a reduction of direct lineof-sight radiation area from the retort proper to the quench bath of about percent.

Another advantage flowing from this substantial reduction in size of the discharge tube relative to the retort is to minimize the size or surface area of the quenching bath. Consequently, with the arrangement of the present invention, the total floor or pit area in a plant is kept at a minimum in relation to the rate of production or flow rate through the industrial furnace of the invention.

While the particular compartmentation in the retort proper as disclosed hereinbefore provides a decided advantage, it is to be understood that an inventive aspect of the development resides in a combination which includes a retort mounted for rotation about a fixed axis of 45(: 5); means for applying heat thereto; a discharge conduit or tube extending from the lower end of the retort; a quench bath beneath and in advance of the retort with regard to the direction of flow of parts or materials being treated, such discharge tube having substantially less transverse dimension than the 1 1 corresponding dimension of the retort and rotating with such retort, the discharge tube having an outlet end portion permanently disposed beneath the liquid level of the quench bath; means being provided to introduce a gaseous atmosphere into the discharge tube at a location at least above the liquid level of this quench bath so as to flow through the retort countercurrent to the flow of workpieces or material therethrough; means are provided to introduce workpieces or material to be treated into the upper-end of the retort; and means are provided within the retort to deflect and feed parts or material to the discharge tube in -response to rotation of the retort and tube. The last mentioned means can comprise the precise structural arrangement disclosed in this application. Altematively, a helix could be disposed on the inner wall of the retort to effect gravitational feed throughout the length of the retort and suitable vanes or deflectors can be as sociated with the interior of the bottom plate of the retort to insure that in response to rotation parts or material are lifted upwardly to enter the inlet-end of the discharge tube for gravitationalflow therethrough and into the quench bath beneath the surface thereof, and either a gravimetric or other volumetric feeder forms may be employed.

What is claimed is: v

l.-ln a rotary industrial furnace for heat treating a plurality of workpieces,

a furnace chamber mounted in an inclined position I at an angle of 45 1 5 to the horizontal,

a retort mounted within said chamber for rotation with respect thereto, said retort having upper and lower ends,

means operatively associated with the upper end of said retort for feeding workpieces to be treated thereinto,

means within said retort permitting step-by-step gravitational advance of workpieces through the retort responsive to unidirectional rotation thereof,

means for imparting continuous unidirectional rotation to said retort;

a quench tank located on the downstream side of said chamber and retort,

a discharge tube means coaxially integrated with the lower end of said retort for rotation therewith, said discharge tube means including a liquid sealed portion located beneath the level of a quenching medium within said tank so that workpieces are directly quenched without exposure to ambient atmospheric conditions thus obviating mechanical seals,

means operatively associated with said discharge tube means for introducing a treatment atmosphere therein above the level of the quench medium therein,

and means for applying heat to the interior of said furnace chamber so as to heat said retort to subject workpieces to heat treatment in a treatment atmosphere as they advance through said retort.

2. A rotary industrial furnace as claimed in claim 1 and said liquid sealed portion of said discharge tube means having substantially less transverse dimension than the transverse dimension of said retort.

3. A rotary industrial furnace as claimed in claim 1 6 comprise axially spaced parallel partitions within said retort extending perpendicular to the axis thereof and dividing the interior thereof into a plurality of-zones, a plurality of radially disposed vanes between adjacent partitions dividing each zone into a plurality of sections, each partition having an aperture therethrough in each section providing communication between the sections of successive zones and deflectors extending generally parallel with the axis of rotation of said retort and operatively related with the apertures in the partitions in at least some of the zones and cooperable with said vanes to lift and guide workpieces from zone to zone successively as said retort rotates.

'4. A rotary industrial furnace as claimed in claim 1 and further including a quench wheel coaxially integrated with said discharge tube means for deflecting workpieces and coincidentally lifting and'horizontally moving same through and from the quench medium to a discharge point exteriorly of and to the rear of said quench tank. I 5. A rotary industrial furnace as claimed in claim 4 and said quench tank having a wall portion perpendicular to the axis of rotation of said retort, a thrust ring coaxial with and carried by said quench wheel and facing said wall portion of said quench tank, and a pair of freely rotatable flanged rollers carried by said wall portion and engaging said thrust ring.

6. A rotary industrial furnace as claimed in claim 1 in which the means operatively associated with the upper end of said retort for feeding workpieces thereinto'include a tubular portion rotatable with said retort and projecting outwardly of the upper end of said chamber, a feedchamber secured to said tubular portion for rotation therewith, vane means dividing said feed chamber into a plurality-of compartments corresponding in number to the number of sections in the uppermost zone of said retort, pipe means providing individual communication between each compartment in said feed chamber and each section of said uppermost zone in said retort, a gravity, cam or otherwise actuated valve controlled inlet into each compartment of said feed chamber, means defining a plurality opentopped compartments, each having such an inlet in the base thereof, and means for feeding workpieces to drop into such open-topped compartments as the same rotate for gravity advance through the respective inlets into the respective compartments of said feed chambers, through said feed chamber compartments to said pipe means and thence into said sections in the uppermost zone of said retort for passage therethrough.

7. A tilted rotary retort industrial furnace for heat treating a plurality of workpieces comprising:

a furnace chamber supported at an angle of 45 i 5 to the horizontal, "said chamber having opposite upper and lower ends having aligned apertures therethrough,

a retort including a body portion of less transverse dimension than the interior transverse dimension of the chamber and opposite tubular end positions journaled in and protruding beyond the apertures in the respective upper and lower ends of the furnace chamber,

means supporting said retort for rotation .within said chamber, 7

means for rotating the retort continuously in one direction,

partitions within the retort, extending perpendicular to the longitudinal axis thereof and dividing the interior of the retort into a plurality of zones, radial vanes between adjacent partitions dividing each zone into a plurality of sections,

each partition having an aperture therethrough in each section providing communication between the sections of successive zones,

deflectors extending parallel with the axis of rotation and operatively associated with the apertures in the partitions in at least some of the zones so that workpieces are lifted and guided from zone to zone successively as the retort rotates,

a quench tank adapted to contain a quenching medium,

the tubular end portion protruding beyond the lower end of said furnace chamber including a portion effecting a liquid seal permanently disposed in and rotating beneath the surface of quenching medium in said tank,

means for introducing a gaseous treatment atmosphere into said last mentioned tubular portion above the level of the quenching medium,

and means for heating the space between the interior of the chamber and the exterior of the retort so that workpieces introduced into the retort via the tubular portion at the upper'end of said furnace chamber are gravitationally advanced step-by-step through successive zones, subjected to heat treatment therein, discharged through such lowermost tubular portion and directly quenched within said quench tank.

8. In a rotary industrial furnace for heat treating a plurality of workpieces, a combination including a retort mounted for rotation about an axis of 45 1 5 to the horizontal,

means for applying unidirectional rotation to said retort, a discharge tube means coaxially integrated with and extending from the lower end of said retort, a quench tank beneath the lower end of said retort, said discharge tube means having substantially less transverse dimension than the corresponding dimension of said retort and including an outlet portion permanently disposed beneath the liquid level of the quench tank,

means for introducing a treatment atmosphere int said discharge tube means at a location therein above the liquid level of the quench tank so as to flow through the retort countercurrent to the direction of flow of workpieces therethrough,

means for introducing workpieces to be treated into the upper end of said retort,

means within the retort to deflect and feed workpieces to said discharge tube means in response to such unidirectional rotation and,

means for applying heat to said retort so as to subject such workpieces to heat treatment in a treatment atmosphere as they advance through said retort.

9. A rotary industrial furnace as claimed in claim 8 and further including means operatively associated with said outlet portion of said discharge tube means for rotation therewith within said quench tank for continuously receiving workpieces and moving such workpieces through and out of said quench tank.

10. in a rotary industrial furnace for heat treating a plurality of workpieces,

a retort having upper and lowerends and supported for rotation about a fixed axis inclined at a high angle of 45 (:5") to the horizontal,

means for imparting unidirectional rotation to said retort,

said retort having an inlet at the upper end thereof into which workpieces to be treated are introduced,

a liquid quenching medium accommodating means below said retort,

a discharge tube means coaxially integrated with and extending from the lower end of said retort and including an outlet portion having substantially less transverse dimension than said retort and so disposed within said liquid quenching medium accommodating means as to be below the level of such a quenching medium so as to provide a permanent and continuously effective liquid seal during operation,

and means within the retort operable in response to the unidirectional rotation thereof, about said fixed axis to provide a continuous steady flow of introduced workpieces through the retort and the selfemptying thereof to and through the outlet portion of said discharge tube means.

11. In a rotary industrial furnace as claimed in claim 10 and means for introducing a treatment atmosphere into said discharge tube means at a location therein above the level of the quench medium.

12. In a rotary industrial furnace as claimed in claim 10 and means operatively connected with said outlet portion of said discharge tube means for rotation there with within the liquid quenching medium accommodating means for continuously receiving workpieces from said outlet portion and moving such workpieces through and out of a liquid quenching medium in said liquid quenching medium accommodating means. 

1. In a rotary industrial furnace for heat treating a plurality of workpieces, a furnace chamber mounted in an inclined position at an angle of 45* + OR - 5* to the horizontal, a retort mounted within said chamber for rotation with respect thereto, said retort having upper and lower ends, means operatively associated with the upper end of said retort for feeding workpieces to be treated thereinto, means within said retort permitting step-by-step gravitational advance of workpieces through the retort responsive to unidirectional rotation thereof, means for imparting continuous unidirectional rotation to said retort; a quench tank located on the downstream side of said chamber and retort, a discharge tube means coaxially integrated with the lower end of said retort for rotation therewith, said discharge tube means including a liquid sealed portion located beneath the level of a quenching medium within said tank so that workpieces are directly quenched without exposure to ambient atmospheric conditions thus obviating mechanical seals, means operatively associated with said discharge tube means for introducing a treatment atmosphere therein above the level of the quench medium therein, and means for applying heat to the interior of said furnace chamber so as to heat said retort to subject workpieces to heat treatment in a treatment atmosphere as they advance through said retort.
 2. A rotary industrial furnace as claimed in claim 1 and said liquid sealed portion of said discharge tube means having substantially less transverse dimension than the transverse dimension of said retort.
 3. A rotary industrial furnace as claimed in claim 1 in which said means within said retort permitting step-by-step gravitational advance of workpieces through the retort responsive to unidirectional rotation thereof comprise axially spaced parallel partitions within said retort extending perpendicular to the axis thereof and dividing the interior thereof into a plurality of zones, a plurality of radially disposed vanes between adjacent partitions dividing each zone into a plurality of sections, each partition having an aperture therethrough in each section providing communication between the sections of successive zones and deflectors extending generally parallel with the axis of rotation of said retort and operatively related with the apertures in the partitions in at least some of the zones and cooperable with said vanes to lift and guide workpieces from zone to zone successively as said retort rotates.
 4. A rotary industrial furnace as claimed in claim 1 and further including a quench wheel coaxially integrated with said discharge tube means for deflecting workpieces 90* and coincidentally lifting and horizontally moving same through and from the quench medium to a discharge point exteriorly of and to the rear of said quench
 5. A rotary industrial furnace as claimed in claim 4 and said quench tank having a wall portion perpendicular to the axis of rotation of said retort, a thrust ring coaxial with and carried by said quench wheel and facing said wall portion of said quench tank, and a pair of freely rotatable flanged rollers carried by said wall portion and engaging said thrust ring.
 6. A rotary industrial furnace as claimed in claim 1 in which the means operatively associated with the upper end of said retort for feeding workpieces thereinto include a tubular portion rotatable with said retort and projecting outwardly of the upper end of said chamber, a feed chamber secured to said tubular portion for rotation therewith, vane means dividing said feed chamber into a plurality of compartments corresponding in number to the number of sections in the uppermost zone of said retort, pipe means providing individual communication between each compartment in said feed chamber and each section of said uppermost zone in said retort, a gravity, cam or otherwise actuated valve controlled inlet into each compartment of said feed chamber, means defining a plurality open-topped compartments, each having such an inlet in the base thereof, and means for feeding workpieces to drop into such open-topped compartments as the same rotate for gravity advance through the respective inlets into the respective compartments of said feed chambers, through said feed chamber compartments to said pipe means and thence into said sections in the uppermost zone of said retort for passage therethrough.
 7. A tilted rotary retort industrial furnace for heat treating a plurality of workpieces comprising: a furnace chamber supported at an angle of 45* + or - 5* to the horizontal, said chamber having opposite upper and lower ends having aligned apertures therethrough, a retort including a body portion of less transverse dimension than the interior transverse dimension of the chamber and opposite tubular end positions journaled in and protruding beyond the apertures in the respective upper and lower ends of the furnace chamber, means supporting said retort for rotation within said chamber, means for rotating the retort continuously in one direction, partitions within the retort, extending perpendicular to the longitudinal axis thereof and dividing the interior of the retort into a plurality of zones, radial vanes between adjacent partitions dividing each zone into a plurality of sections, each partition having an aperture therethrough in each section providing communication between the sections of successive zones, deflectors extending parallel with the axis of rotation and operatively associated with the apertures in the partitions in at least some of the zones so that workpieces are lifted and guided from zone to zone successively as the retort rotates, a quench tank adapted to contain a quenching medium, the tubular end portion protruding beyond the lower end of said furnace chamber including a portion effecting a liquid seal permanently disposed in and rotating beneath the surface of quenching medium in said tank, means for introducing a gaseous treatment atmosphere into said last mentioned tubular portion above the level of the quenching medium, and means for heating the space between the interior of the chamber and the exterior of the retort so that workpieces introduced into the retort via the tubular portion at the upper end of said furnace chamber are gravitationally advanced step-by-step through successive zones, subjected to heat treatment therein, discharged through such lowermost tubular portion and directly quenched witHin said quench tank.
 8. In a rotary industrial furnace for heat treating a plurality of workpieces, a combination including a retort mounted for rotation about an axis of 45* + or - 5* to the horizontal, means for applying unidirectional rotation to said retort, a discharge tube means coaxially integrated with and extending from the lower end of said retort, a quench tank beneath the lower end of said retort, said discharge tube means having substantially less transverse dimension than the corresponding dimension of said retort and including an outlet portion permanently disposed beneath the liquid level of the quench tank, means for introducing a treatment atmosphere into said discharge tube means at a location therein above the liquid level of the quench tank so as to flow through the retort countercurrent to the direction of flow of workpieces therethrough, means for introducing workpieces to be treated into the upper end of said retort, means within the retort to deflect and feed workpieces to said discharge tube means in response to such unidirectional rotation and, means for applying heat to said retort so as to subject such workpieces to heat treatment in a treatment atmosphere as they advance through said retort.
 9. A rotary industrial furnace as claimed in claim 8 and further including means operatively associated with said outlet portion of said discharge tube means for rotation therewith within said quench tank for continuously receiving workpieces and moving such workpieces through and out of said quench tank.
 10. In a rotary industrial furnace for heat treating a plurality of workpieces, a retort having upper and lower ends and supported for rotation about a fixed axis inclined at a high angle of 45* ( + or - 5*) to the horizontal, means for imparting unidirectional rotation to said retort, said retort having an inlet at the upper end thereof into which workpieces to be treated are introduced, a liquid quenching medium accommodating means below said retort, a discharge tube means coaxially integrated with and extending from the lower end of said retort and including an outlet portion having substantially less transverse dimension than said retort and so disposed within said liquid quenching medium accommodating means as to be below the level of such a quenching medium so as to provide a permanent and continuously effective liquid seal during operation, and means within the retort operable in response to the unidirectional rotation thereof, about said fixed axis to provide a continuous steady flow of introduced workpieces through the retort and the self-emptying thereof to and through the outlet portion of said discharge tube means.
 11. In a rotary industrial furnace as claimed in claim 10 and means for introducing a treatment atmosphere into said discharge tube means at a location therein above the level of the quench medium.
 12. In a rotary industrial furnace as claimed in claim 10 and means operatively connected with said outlet portion of said discharge tube means for rotation therewith within the liquid quenching medium accommodating means for continuously receiving workpieces from said outlet portion and moving such workpieces through and out of a liquid quenching medium in said liquid quenching medium accommodating means. 